In lighting engineering, it is very important to choose appropriate lamps and lanterns. In the selection of lamps and lanterns, we should comprehensively consider various factors, including the efficiency of lamps and lanterns, the light distribution characteristics of lamps and lanterns, the use of the environment, the light maintenance performance of lamps and lanterns, etc.
The efficiency of lamps is closely related to energy saving. If lamps and lanterns efficiency is too low, it is difficult to remedy its energy-saving effect with other methods. China has yet to announce clear requirements for lamp efficiency. Now, THE RELEVANT LUMINAIRE EFFICIENCY PART IN THE 1990 NOTICE OF THE Ministry of Light Industry (90) Light WORD No. 25 “The Quality and Inspection Level of the Ministry OF Industrial and Mining Civil ENERGY-SAVING LUMINAIRE” IS listed, as shown in Table 7.9.
In order to reduce the loss of light, should be as far as possible to use the lamp with no shading accessories. The grille, prism, plexiglass plate and opalescent glass cover with the luminaires are called luminaires accessories. The function of these accessories is to change the direction of light, reduce glare, and increase aesthetic and decorative effects. However, these accessories will cause the decrease of light output and the increase of power consumption, which is detrimental to energy saving. In Table 7.10, the proportion of light lost by the addition of accessories to factory diffused lamps and recessed fluorescent lamps is shown. If these lamps with shading accessories are polluted, their light output will be further affected, and the efficiency of the lamps will be reduced by 5%-6%. Accordingly, BELOW the CONDITION THAT ASSURES ILLUME QUALITY, SHOULD CHOOSE OPEN TYPE LAMPS AND LANTERNS as FAR AS POSSIBLE.
When CHOOSING LAMPS AND LANTERNS, SHOULD MAKE ITS GIVE OUT RADIANT FLUX TO FALL TO THE WORKING SURFACE TO THE GREATEST EXTENT, HAVE TALLER USE COEFFICIENT NAMELY. The utilization factor depends on lamp efficiency, lamp distribution, interior decoration and other factors. The EXPERIMENTAL ANALYSIS SHOWS THAT THE MAIN FACTOR AFFECTING THE utilization COEFFICIENT IS the direct light flux of the LAMP IN general, because when the height of the room changes, the change of the reflected light flux is small. In short and wide rooms, the ratio of room space is smaller, most of the direct light flux falls on the working surface, and the utilization coefficient is higher. High and narrow room room space is larger, direct light falling on the work surface is reduced, the utilization coefficient is reduced. In the specific lighting design, the room space ratio is a constant value, in order to improve the utilization coefficient, the light flux of lamps and lanterns should be more evenly distributed on the working surface. In addition, when choosing the light distribution of lamps and lanterns, also consider the requirement of limiting glare. Luminaires with surface brightness limits and shading angles shall be used.
According to the environmental conditions of the lighting place, choose the following lamps and lanterns respectively.
① In humid places, waterproof lamps with corresponding protection grade or open lamps with waterproof lamp cap should be used.
(2) In the place with corrosive gas or steam, anti-corrosion sealing lamps should be used. If open lamps and lanterns are used, all parts should be corrosion or waterproof measures.
③ In high temperature places, it is appropriate to use lamps with good heat dissipation performance and high temperature resistance.
(4) In the place of dust, the appropriate luminaires should be selected according to the corresponding dustproof grade. ⑤ In the use of forging hammer, large bridge crane vibration, swing places such as lamps and lanterns, should be anti vibration and anti falling measures.
⑥ In the vulnerable to mechanical damage, light source off may cause personnel injury or property loss of the place used lamps, there should be protective measures.
⑦ Lamps and lanterns used in places with explosion or fire hazards should comply with the relevant provisions of current national standards and norms, such as the Code for Electric Power Design in Explosion and Fire Hazardous Environments.
⑧ In places with clean requirements, should be used not easy to dust, easy to wipe clean lamps and lanterns.
⑨ In places that need to be protected from ultraviolet radiation, purple-isolated lamps or non-ultraviolet light sources should be used.
The decrease of luminaires’ luminous flux includes the decrease of luminaires’ luminous flux (light decay) and the decrease of luminaires’ output efficiency caused by luminaires’ aging pollution. Lamps with high retention rate should be used as far as possible. In the commonly used lighting source, the light flux of high pressure sodium lamp decreases the least during its life, and the light flux at the end of life decreases by about 17%; The light flux of metal halide decreased greatly, and the light flux at the end of life decreased about 30%. The final luminous flux of high pressure mercury fluorescent lamp is reduced by about 20%. In order to reduce the decrease of luminaire efficiency caused by luminaire aging, several measures can be taken. Aluminum reflectors, for example, are often anodized to create an aluminum oxide film to prevent lamps from aging. Lamps with high retention rate are generally coated with a layer of pure quartz glass (SiO2) on the surface of the lampshade. On the one hand, this can improve the heat-resistant impact performance, enhance the flexural strength, improve the smoothness of the surface, not easy to accumulate ash, and easy to wash with water; On the other hand, high purity SiO2 has corrosion resistance to acids and bases (except hydrofluoric acid) and can be used for a long time in corrosive environments. Table 7.11 compares the corrosion resistance of high purity quartz glass and alumina film.
In addition, for a closed lamp, when the lamp is at the ignition point, the internal temperature of the lamp rises, the air expands, the internal pressure increases, and the air flows out from the tiny pores in the lamp. When the lamp is turned off, the internal temperature of the lamp drops, the internal pressure drops, and the outside air flows into the lamp through the air hole. At this moment, the dust of the outside world also can flow in together with the air, lamps and lanterns can be polluted. In order to prevent this type of pollution, it is necessary to set up special pores on the lamp, and install activated carbon filters in the pores to absorb dirt in the outside air and other components that may have adverse effects on the lamp, such as nitrogen dioxide, sulfur dioxide and other hydrocarbon gases. Table 7.12 compares the changes of light efficiency of two kinds of sealed lamps with and without activated carbon filtration during their life. As can be seen from the table, after 4 years of use, the light output of the lamps without filter equipment decreased by 13% compared with the initial period. Lamps with filters had only a 2 percent reduction. From another side can be seen in the use of the maintenance of lamps and lanterns is very important.